1. Field of the Invention
The present invention relates generally to snap rings and, more particularly, to a snap ring having multiple rollers which couples a purse line and a purse seine, which are used for fishing, to each other.
2. Description of the Related Art
As well known to those skilled in the art, purse seines are one kind of fishing net and fishing equipment used for fishing for sardines, horse mackerels, mackerels, bonitos, tuna, etc. Such a purse seine and a conventional snap ring are illustrated in FIGS. 1 and 2.
As shown in FIGS. 1 and 2, a purse seine 110 has a rectangular shape, the central portion of which is slightly wider than other portions. Furthermore, a plurality of buoyancy units 120 is provided along the upper edge of the purse seine 110 in order to make it possible for the upper edge of the purse seine 110 to float on water, and bridle chains 125 are provided under the lower edge of the purse seine 110 so as to make it possible for the lower edge of the purse seine 110 to sink under the water surface. Thus, the buoyancy units 120 and the bridle chains 125 can orient the purse seine 110 upright in the water. Typically, the purse seine 110 expands in the water into an approximately circular shape so as to catch fish.
Furthermore, a purse line 130 which is used to haul in the purse seine 110 which has expanded into a circular shape is disposed along the lower edge of the purse seine 110. The purse line 130 is coupled to ends of the bridle chains 125 through connectors which are called snap rings 140. In detail, connection members 127 such as ropes are connected to the ends of the bridle chains 125. Each connection member 127 is connected to a first end of the corresponding snap ring 140. The purse line 130 passes through second ends of the snap rings 140, thereby coupling the purse line 130 to the bridle chains 125.
To haul in the purse seine 110, when the purse line 130 is pulled by a hydraulic purse winch provided on a fishing boat 150, the bridle chains 125 of the purse seine 110 are also pulled, and thus fish are confined while the purse seine 110 is hauled in.
However, in the case of the snap ring 140 according to the conventional technique, due to the weight of the fish and the purse seine 110 being hauled in, a relatively large frictional force is generated on the contact surface between the purse line 130 and the snap rings 140, thus inducing extreme abrasion of the surfaces of the purse line 130 and the snap rings 140, possibly resulting in tearing. This seriously interferes with the fishing operation. Furthermore, maintenance costs increase due to frequent replacement of the purse line 130 or the snap ring 140, thus resulting in reduced income.